This application is in response to NOT-OD-09-058: NIH announces the Availability of Recovery Act Funds for Competitive Revision Applications. The Cornea Donor Study (CDS) and its ancillary study, the Specular Microscopy Ancillary Study (SMAS), are examining the effect of donor age and the predictive value of endothelial cell density (ECD) on cornea graft survival. The study enrolled 1,101 subjects undergoing penetrating keratoplasty at 80 clinical sites in the United States between January 10, 2000 and August 2, 2002;the SMAS included 596 subjects from 45 clinical sites. Changes in the morphometric parameters of cell area, coefficient of variation reflecting variation in cell size (polymegathism), and percentage of hexagonal cells reflecting variation in cell shape (pleomorphism), may be more sensitive than endothelial cell density in assessing endothelial health and dysfunction. As a result, a pilot study, which is currently in progress was developed to determine the feasibility and reliability of implementing established morphometric analysis methods to determine morphometric parameters on a select set of the SMAS images of varying quality. As part of the pilot study, the Case Western Reserve University Specular Microscopy Reading Center (SMRC), which serves as the central reading center for the SMAS, is defining the procedures for morphometric analyses of images received in the SMAS. To date, we have found that a flexible application of these available methods based upon image quality will enable us to acquire these data on the majority of images encountered in the first 5 years of the SMAS. We propose that the morphometric analysis should be expanded to include all images received in the first five years of the SMAS. This is a unique opportunity to obtain additional data from this ongoing longitudinal study which will allow us to determine the value of changes in the various endothelial parameters over a 5-year period after penetrating keratoplasty on endothelial function and ultimate decompensation.